magma series mantle

Question 1

reflects the isotopic signature of the primitive mabtle as it would evolve to the present w/o any subsequent fractionation of the radioactive elements extracted to form continental and oceanic crust

Answer 1

BSE Bulk Silicate Earth

Question 2

high pb 206/ Pb 204 ration suggestive of a source with high au but it is not enriched in Rb low Sr87/Sr86 old enough >1 Ga to develop the observed isotopic ratios by radioactive decay over time

Answer 2

HIMU (High myu)

Question 3

high He3 and He 4 mantle reservoir act as a mixing conponent and explain the spread of OIB data in the He Sr Nd Pb systems

Answer 3

PHEM primitive Helium Mantle

Question 4

represents a restricted isotopic range tht is common in ocean volcanic rocks

Answer 4

PREMA (Prevalent Mantle)

Question 5

a high He3/He4 component lying approx midway between DM and HIMU that representd actual source material (a true mantle reservoir) or the partial melting process in rising OIB diapirs wc sampla a mixed DM-HIMU source in very consistent proportions

Answer 5

FOZO Focal Zone

Question 6

restricted intermediate isotopic value where the convergence of Pb Nd Sr isotopic data for MORB and OIBs approaches a high He3/ He4 reservoirs

Answer 6

Common Mantle

Question 7

source of N type MORB

Answer 7

DM reservoir

Question 8

less wnriched and may also represent a crustal componentn either ancient oceanic crust or pelagic sediment or they may possibly have been entiched by intra mantle processes stranded melts or metasomatizing fluids

Answer 8

EMI and HIMU reservoirs

Question 9

contain non depleted BSE partially depleted PREMA and non degassed FOZO PURM and C

Answer 9

OIB

Question 10

region along the immediate plate boundary eithin wc volcanism is concentrated is also assoc with very high heat flow indicating an elevated geothermal gradient

Answer 10

neovolcanic zone

Question 11

locus of considerable earthquake activity

Answer 11

ridge axis

Question 12

formed where hydrothermal fluids in excess of 350 C cool dramatically upob escaping from vents and precipitate a number of minerlas including barite silica and several valuable metal sulfides

Answer 12

spires chimneys

Question 13

subduction rate of island arc

Answer 13

0.9-10.8 cm/yr

Question 14

arc type crust range

Answer 14

from 12-36 km
averages about 36km

Question 15

stable only if the melt contains >3 wt. % H2O excess of 0.1 to 0.2 Gpa

Answer 15

black hornblende

Question 16

correspond to steey dipping 25-30 seents of yhe subducting slab

Answer 16

active volcanic zones

Question 17

correspond to zegments with much dhallowet dips 10-15 degrees of a segmented Nazca plate

Answer 17

inactive volcanic zones

Question 18

originates from the fluid fluxed and LIL enriched mantle wedge above the subducting and dehydrating Nazca plate jn the same manner

Answer 18

andean magmatism

Question 19

extends for about 1000km and corresponds to the length of the juan de fuca plate system subducting obliquely beneath the north american plate

Answer 19

cascade magmatic arc

Question 20

100-300km long by 10-25 km wife tectonic slices of mafic to silicic volcaniclastic clastic and chemical sediments some tectonic melanges

Answer 20

greenstone belts

Question 21

alkali picrite

Answer 21

ankaramite

Question 22

co2 rich and less potassic than group 2 kimberlite

Answer 22

group I kimberlite

Question 23

h2o rich and has a mica rich matrix

Answer 23

group II kimberlite (orangeite)

Question 24

also known alkali basalts lamprophyres alpine peridotites 1-1.4 g percton and occur only underlain by rocks older than 2.5 Ga

Answer 24

diamonds

Question 25

dikes near the top into lenticular enlargement up to 10-20 times the file width and 100 m long

Answer 25

blows

Question 26

revised term for epiclastic

Answer 26

resedimented volcaniclastic kimberlite RVK

Question 27

revised term for tuff ring

Answer 27

pyroclastic kimberlite PK

Question 28

revised term for tuffisitic kimberlite breccia TKB

Answer 28

massive volcaniclastic kimberlite MVK

Question 29

generated by low degrees of partial melting of hydrated carbonated peridotite

Answer 29

kimberlites

Question 30

what were the original shallow water supracrustal sediments

Answer 30

politic schists quartzites and marbles

Question 31

mantle xenoliths from kimberlites record pressures up to 4 GPa >120 km but are given igneous names

Answer 31

lherzolite

Question 32

critical point of pure h2o is at 374 C and 21.8 MPa

Answer 32

hmm

Question 33

resulting metamorhic rocks thus tyicalky display nearly random textural favrics and may generally be called

Answer 33

granofels

hornfels if hard and compact

Question 34

muscovite is absent and plag and ortho are common

Answer 34

granulite

Question 35

mica rich mylonite

Answer 35

phyllonite

Question 36

impact craters may have macroscopic nested cone like structures

Answer 36

shatter cones